Sensing fluid flow using vortex street generation is simple, inexpensive, and robust, but it suffers from limitations in range of flow velocities; it also suffers from slow response and relatively large measurement error at low flow velocities.
Scaling the fluid flow velocity by using converging and/or diverging channels adjusts the flow velocity to a range suitable for production of measurable vortex streets.
Multiple channels with different velocity scalings for different vortex sensors greatly extends the usable range of the vortex sensor method by choosing the most-sensitive sensor which has not saturated (exceeded its maximum sensible flow velocity). Sensors in the same assembly, having fluid flows exceeding their ability to respond, are not damaged due to the rugged nature of the basic method. Using the most-sensitive sensor that has not saturated reduces both measurement error and measurement time; reduced measurement time speeds response to a change in flow rate.
Another improvement is using multiple channels with bluff bodies of differing widths or shapes to produce multiple vortex frequencies from the same flow. This provides extends the range of sensible vortex streets. This method can also be combined using different channel flow velocity scalings as desired.
Vortex flow meters are easily linearized and are very robust. They compete with methods such as hot-wire, hot-film, and moving-vane meters; these other methods have had greater dynamic range or speed-of-response, but are not as reliable and robust. Methods described here improve vortex flow meters' response characteristics to meet or exceed those of competing methods, while maintaining the robust and low-cost advantages of the vortex method.
Vortex flow meters are very commonly used to sense airflow into internal combustion engines, but they have applications in metering fluids in a wide variety of settings. They can also be used to measure coolant, lubricating oil, and fuel flow in engines. Vortex flow meters can be used to meter combustion or ventilation airflow in HVAC units (which currently use moving-vane detectors). They have also found applications in pipelines carrying diverse fluids such as water, natural gas, and other fuels.
Vortex flow meters, when used in piston engine intakes, frequently save significant fuel due to their excellent reliability as competing types of flowmeters frequently age and fail in ways that cause excess fuel to be metered out by the engine controller.